Hummer with bouncing rpms
 

I was wondering if anyone could help me/ I have a 2003 hummer h2 and when i go around curves it jumps like my foot is coming off of the gas peddle. the rpms will go up and down a little. It only does it around curves and mostly early in the day. If i drive it a little, it will almost stop doing it. I have had the fluid changed in the back end and the fuel pump filter changed, but it still does it.